The present invention relates to a gateway apparatus mounted on a vehicle.
In recent vehicles, a plurality of electronic control units (referred to as ECUs) such as an ECU for an engine control, an ECU for a door control, an ECU for an airbag, and an ECU for navigation are mounted. A gateway apparatus for connecting these ECUs via a plurality of networks has been proposed such that these ECUs can communicate with each other.
Japanese Patent Publication Laid-Open (JP-A) No. 2008-172353 discloses a vehicle onboard relay apparatus (gateway apparatus) for providing a sending queue for each of ports corresponding to connected plurality of networks, adding sender information to received data, determining an order in which the received data is sent based on the sender information and a priority (ID) of the received data, and storing the received data in the sending queue of the port of a network to which the received data is to be sent.
A plurality of electronic control units (ECUs) mounted on a vehicle perform various controls for various parts of the vehicle. The controls have various contents, and various kinds of data are sent and received between in-vehicle networks. By establishing a priority order for various kinds of data, data having a higher priority can be preferentially transferred as compared to data having a lower priority. On the other hand, for some kinds of data, it is desired to perform the data transfer in a fixed order. If the data transfer according to the priority is performed for all the cases, the order of sending of such kinds of data may be disturbed.
In the configuration of the gateway apparatus in the above patent document, data transfer is performed in the order of priority. On the other hand, the gateway apparatus uses the sender information to determine whether data is received from the same network or from the same onboard communication apparatus. The order in which the data is sent is maintained for data received from the same network or the same onboard communication apparatus.
Because the sender information is used, it is required, when the received data is stored in the sending queue, to compare not only the priority of the received data but also the sender information with data already stored in the sending queue, which may increase a processing load. Such a load may also increase in accordance with the number of the stored data, and hence a time period from receiving data to sending the data may increase. Because the sender information is added, the amount of transferred data may increase.
Therefore, a vehicle onboard gateway apparatus that is capable of sending data in the order of priority for one kind of data while sending data in the order in which the data is received for the other kind of data, with avoiding an increase of a processing load, is desired.